Abstract
Shiga toxin-producing Escherichia coli (STEC) causes serious human illness such as hemolytic uremic syndrome (HUS). Argentina has the world’s highest rate of this syndrome, which is the leading cause of acute renal failure among children. E. coli O157:H7 is the most common cause of HUS, but a substantial and growing proportion of this illness is caused by infection due to non-O157 strains. Multiple-locus variable-number tandem repeat analysis (MLVA) has become an established technique to subtype STEC. This review will address the use of routine STEC subtyping by MLVA in order to type this group of isolates and to get insight into the genetic diversity of native STEC. With regard to these objectives we modified and adapted two MLVA protocols, one exclusive for O157 and the other, a generic E. coli assay. A total of 202 STEC isolates, from different sources and corresponding to 20 serotypes, have been MLVA genotyped in our laboratory. In our experience, MLVA constitutes a very sensitive tool and enables us to perform an efficient STEC subtyping. The diversity found in many serotypes may be useful for future epidemiological studies of STEC clonality, applied to O157 as well as to non-O157 isolates.
Highlights
Edited by: Analía Inés Etcheverría, Universidad Nacional del Centro de la Provincia de Buenos Aires, Argentina
E. coli O157:H7 is the most common cause of hemolytic uremic syndrome (HUS), but a substantial and growing proportion of this illness is caused by infection due to non-O157 strains
This review will address the use of routine Shiga toxin-producing Escherichia coli (STEC) subtyping by Multiple-locus variable-number tandem repeat analysis (MLVA) in order to type this group of isolates and to get insight into the genetic diversity of native STEC
Summary
Our laboratory is focused on implementing multiple-locus variable-number tandem repeat analysis (MLVA) as genotyping method, which will be reviewed here. A total of 202 STEC isolates, tested previously for selected virulence factors, has been MLVA genotyped in our laboratory between 2006 and 2010 They have been isolated from bovines, foods, and patients in previous studies (Parma et al, 2000; Padola et al, 2004; Sanz et al, 2007; Fernández et al, 2010a; Rivero et al, 2010). We observed variation at all nine loci and the most variable locus was TR2, coincidently with the results of Hyytiä-Trees et al (2006) and Noller et al (2006)
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